In the design of gears, one of the main limiting factors in the load capacity of a given gear is the bending strength of its teeth. Although it is known to increase bending strength by selecting gear teeth having a corser pitch, this has been found to normally reduce the gear's load capacity in other types of failure modes such as pitting and scuffing. Many strategies are known for increasing bending strength of a gear without altering the general gear design, including, but not limited to, use of better materials, hardening methods, and shot peening.
Another strategy would be to reduce the peak bending stress value of a gear tooth without changing the basic tooth dimensions. In this regard, it is known that the typical location for the peak bending stress is the tooth fillet which encompasses a transition area extending between the start of an active profile region of the tooth wherein it engages teeth of a mating gear and the root of the tooth where it joins the gear body. An ideal stress reduction strategy would reduce the stress gradient along the tooth fillet such that high stress concentrations are not present.
Accordingly, the present invention is directed to achieving one or more of the objectives as set forth above.